Organic waste material digestion apparatus and system

Abstract

System and apparatus for treating organic waste material, suited, for example, for the aerobic-thermophilic treatment of cattle manure. The waste material initially is commingled with an expanded, size limited dry cellulosic material in a mixing stage, preferably, a pug mill device, to achieve a bulk density and moisture content optimized for thermophilic digestion. A digestion arrangement is provided assuming a reliability for complete aerobic treatment of all material removed therefrom.

We claim: 
     
       1. Organic waste material digestion apparatus comprising: a receptacle of generally cylindrical surface configuration having a circular top edge portion, a bottom portion supportable upon a base and exhibiting height and right cross-sectional diameter dimensions for retaining a predetermined volume of said waste material;   means for supplying oxygen-laden gas under pressure;   conduit means connected with said means for supplying gas, positioned within said receptable at the level of the said bottom portion, including a plurality of spaced gas outlets arranged in a pattern for effecting an aerobic influence over substantially all said organic waste material deposited within said receptacle by gas issuing from said outlets;   diffuser means positioned within said receptacle, having an upward surface supporting said waste material above said conduit means for effecting a diffusion of said gas issuing from said outlets;   support means extending diametrically across said receptacle and supported upon said receptacle circular top portion and rotatable thereupon about the centrally diposed axis of said cylindrical surface;   input means supported upon and rotatable with said support means for delivering said waste material to said receptacle by deposition thereinto through said support means in the vicinity of said cylindrical surface;   agitator means including rotational, auger-type agitators supported by and extending from said support means substantially to the upwardly disposed surface of said diffuser means, said agitators being serially disposed and mutually spaced within two substantially parallel rows each extending from the vicinity of said centrally disposed axis toward said cylindrical surface and of number sufficient to confront substantially the entirety of said waste material upon a complete revolution of said support means about said axis; and   output means including an orifice centrally located at said axis of said cylindrical surface at the said upward surface of said diffuser means, said orifice having a peripheral extent substantially small with respect to the peripheral extent of said cylindrical surface; and   at least one said auger-type agitator being positioned above at least a portion of said output means orifice so as to effect an agitation of digested said waste material located thereabove.   
     
     
       2. The organic waste material digestion apparatus of claim 1 in which said agitator means includes agitator drive means for rotating said auger-type agitators at incrementally diminishing velocities with respect to the relative positions thereof progressing from said cylindrical surface toward said centrally disposed axis. 
     
     
       3. The organic waste material digestion apparatus of claim 1 including support means drive means drivably connected between said support means and said circular top portion for effecting the rotation of said support means about said centrally disposed axis at a predetermined rate. 
     
     
       4. The organic waste material digestion apparatus of claim 3 in which said support means drive means includes a first drive component mounted upon said cover at one given position adjacent said cylindrical surface, and a second drive component mounted upon said support means at a position adjacent said cylindrical surface substantially diametrically opposite said given position. 
     
     
       5. The organic waste material digestion apparatus of claim 1 wherein said support means is present as a rigid continuous cover and including a flexible seal positioned in a slideable adjacency intermediate said receptacle circular top edge portion and said rigid cover. 
     
     
       6. A system for treating organic waste material, including animal waste such as manure and the like, comprising: receiving station means for receiving said waste material in an aerobically untreated state;   means for providing a size-limited and expanded cellulosic material;   mixing means for receiving, agitating and retaining for a predetermined interval both said waste material and said cellulosic material to provide a bulk density adjusted biodegradable material the bulk density and moisture content of said waste material being lowered at the termination of said predetermined interval to a value optimized for the thermophilic biodegradation thereof;   means for transferring said bulk density adjusted biodegradable material to a digester station means;   digester station means for inducing the aerobic decomposition of said density adjusted biodegradable material and including:   a receptacle of generally cylindrical surface configuration having a circular top edge portion, a bottom portion supportable upon a base ane exhibiting height and right cross sectional dimensions for retaining a predetermined volume of said bulk density adjusted biodegradable material;   means supplying oxygen-laden gas under pressure;   conduit means connected with said source of gas, positioned within said receptacle at the level of said bottom portion, including a plurality of spaced gas outlets arranged in a pattern for effecting an aerobic influence over substantially all of said density adjusted biodegradable material deposited within said receptacle by gas issuing from said outlets;   diffuser means positioned within said receptable, having an upward surface supporting said waste material above said conduit means for effecting a diffusion of said gas issuing from said outlets;   support means extending diametrically across said receptacle and supported upon said receptacle circular top portion and rotatable thereupon about the centrally disposed axis of said cylindrical surface;   input means supported upon and rotatable with said support means for delivering said density adjusted biodegradable material from said transferring means thereinto through said support means in the vicinity of said cylindrical surface;   agitator means including rotational, auger-type agitators supported by and extending from said support means substantially to the upwardly disposed surface of said diffuser means, said agitators being serially disposed and mutually spaced within two substantially parallel rows each extending from the vicinity of said centrally disposed axis toward said cylindrical surface and of number sufficient to confront substantially the entirety of said bulk density adjusted biodegradable material upon a complete revolution of said support means about said axis, said agitator means and said diffused oxygen laden gas effecting a progressive diminution of the biochemical oxygen demand of said material;   output means including an orifice positioned at said axis of said cylindrical surface at the said upward surface of said diffuser means for removing said material evidencing a lowest biochemical oxygen demand value within said receptacle and designated compost material;   at least one said auger-type agitator being positioned above at least a portion of said output means orifice so as to effect an agitation of digested compost material located immediately above; and   means for transferring said compost material to storage and post-treatment stages.   
     
     
       7. The system for treating organic waste material of claim 6 in which said cellulosic material is straw, and wherein said means for providing said size limited and expanded material includes a stage for shredding said straw prior to said mixing means reception thereof. 
     
     
       8. The system for treating organic waste material of claim 6 wherein said mixing means includes means for retaining and agitating said waste and cellulosic materials in the presence of a water adjuvant in an amount sufficient for deriving a moisture content for said bulk density adjusted biodegradable material within a range of about fifty to sixty percent by weight. 
     
     
       9. The system for treating organic waste material of claim 6 wherein said cellulosic material is an inert, coarse, void defining material and said post-treatment stages include means for removing said inert, coarse, void defining material from said compost material.   
     
     
       10. A method for aerobically treating animal waste material comprising the steps of: receiving said material at a receiving station;   providing a biodegradable cellulosic material having a moisture content of value below that of said animal waste material;   shredding said cellulosic material to provide a size-limited and expanded biodegradable material;   mixing said size-limited and expanded biodegradable material with said animal waste material for an interval predetermined to provide a biodegradable material exhibiting a first value of biochemical oxygen demand and a bulk density and moisture content optimized for the efficient thermophilic aerobic reaction thereof induced by the passage of oxygen laden atmospheric air therethrough;   transferring said material of first value biochemical oxygen demand to a digester to provide a bulk quantity of said material supported upon a surface of said digester and extending about a given perimeter thereof;   passing oxygen laden atmospheric air from said surface through said bulk quantity of said material;   simultaneously agitating said bulk quantity of said material in a manner promoting the generally alternating vertical movement of said material from said supporting surface to the uppermost surface of said bulk material as well as the migration thereof toward a point of removal from said digester and to simultaneously promote a progressive dimunition of said first value biochemical oxygen demand said agitation including the agitation of said bulk quantity of said material at a position substantially over said point of removal;   removing said migrated material of lowest value biochemical oxygen demand substantially only from the lowermost level of said bulk thereof at said point of removal substantially at the center of said digester; and   transferring said removed material to a receiving station.   
     
     
       11. The method of claim 10 in which said waste material is cow manure and said biodegradable cellulosic material is straw. 
     
     
       12. The method of claim 10 in which the rate of said passage of oxygen laden atmospheric air is regulated in correspondence with said progressive dimunition of said value of first value biochemical oxygen demand. 
     
     
       13. The method of claim 10 wherein said agitation of said bulk quantity of said material is carried out within said digester under oxygen laden atmospheric air pressure greater than the corresponding environmental atmospheric air pressure. 
     
     
       14. The method of claim 10 wherein said expanded cellulosic material is characterized in having a moisture content less than the moisture content of said animal waste material.